That would lead me to think it was a original six pack motor. I am not aware of a 70 4 barrel motor with 4 valve relief pistons. The factory replacement piston for a 70 4 barrel should be L2266F (hp and nonhp)..a flat top about .080 down the deck.
Although we call them six pack rods, they were simply called HD rods. Lots of different pistons got hung on them, including low compression pistons.
At the factory mopar was known to do different things on the assembly line and it is possible someone on the line used a six pack piston on a 4 barrel. But I have never run across it. The original parts manual would say.
The pistons I have seen in 440s don't have any relation to what rods were in it, but they do to the year and application. They used a lot of different balancers as well with forged cranks both internal and external balanced.
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